drivers/watchdog/coh901327_wdt.c

   1 /*
   2  * coh901327_wdt.c
   3  *
   4  * Copyright (C) 2008-2009 ST-Ericsson AB
   5  * License terms: GNU General Public License (GPL) version 2
   6  * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
   7  * Author: Linus Walleij <linus.walleij@stericsson.com>
   8  */
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/watchdog.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/pm.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/io.h>
  16 #include <linux/bitops.h>
  17 #include <linux/clk.h>
  18 #include <linux/delay.h>
  19 #include <linux/err.h>
  20
  21 #define DRV_NAME "WDOG COH 901 327"
  22
  23 /*
  24  * COH 901 327 register definitions
  25  */
  26
  27 /* WDOG_FEED Register 32bit (-/W) */
  28 #define U300_WDOG_FR                                                    0x00
  29 #define U300_WDOG_FR_FEED_RESTART_TIMER                                 0xFEEDU
  30 /* WDOG_TIMEOUT Register 32bit (R/W) */
  31 #define U300_WDOG_TR                                                    0x04
  32 #define U300_WDOG_TR_TIMEOUT_MASK                                       0x7FFFU
  33 /* WDOG_DISABLE1 Register 32bit (-/W) */
  34 #define U300_WDOG_D1R                                                   0x08
  35 #define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER                            0x2BADU
  36 /* WDOG_DISABLE2 Register 32bit (R/W) */
  37 #define U300_WDOG_D2R                                                   0x0C
  38 #define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER                            0xCAFEU
  39 #define U300_WDOG_D2R_DISABLE_STATUS_DISABLED                           0xDABEU
  40 #define U300_WDOG_D2R_DISABLE_STATUS_ENABLED                            0x0000U
  41 /* WDOG_STATUS Register 32bit (R/W) */
  42 #define U300_WDOG_SR                                                    0x10
  43 #define U300_WDOG_SR_STATUS_TIMED_OUT                                   0xCFE8U
  44 #define U300_WDOG_SR_STATUS_NORMAL                                      0x0000U
  45 #define U300_WDOG_SR_RESET_STATUS_RESET                                 0xE8B4U
  46 /* WDOG_COUNT Register 32bit (R/-) */
  47 #define U300_WDOG_CR                                                    0x14
  48 #define U300_WDOG_CR_VALID_IND                                          0x8000U
  49 #define U300_WDOG_CR_VALID_STABLE                                       0x0000U
  50 #define U300_WDOG_CR_COUNT_VALUE_MASK                                   0x7FFFU
  51 /* WDOG_JTAGOVR Register 32bit (R/W) */
  52 #define U300_WDOG_JOR                                                   0x18
  53 #define U300_WDOG_JOR_JTAG_MODE_IND                                     0x0002U
  54 #define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE                              0x0001U
  55 /* WDOG_RESTART Register 32bit (-/W) */
  56 #define U300_WDOG_RR                                                    0x1C
  57 #define U300_WDOG_RR_RESTART_VALUE_RESUME                               0xACEDU
  58 /* WDOG_IRQ_EVENT Register 32bit (R/W) */
  59 #define U300_WDOG_IER                                                   0x20
  60 #define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND                           0x0001U
  61 #define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE                          0x0001U
  62 /* WDOG_IRQ_MASK Register 32bit (R/W) */
  63 #define U300_WDOG_IMR                                                   0x24
  64 #define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE                              0x0001U
  65 /* WDOG_IRQ_FORCE Register 32bit (R/W) */
  66 #define U300_WDOG_IFR                                                   0x28
  67 #define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE                        0x0001U
  68
  69 /* Default timeout in seconds = 1 minute */
  70 static unsigned int margin = 60;
  71 static resource_size_t phybase;
  72 static resource_size_t physize;
  73 static int irq;
  74 static void __iomem *virtbase;
  75 static struct device *parent;
  76
  77 /*
  78  * The watchdog block is of course always clocked, the
  79  * clk_enable()/clk_disable() calls are mainly for performing reference
  80  * counting higher up in the clock hierarchy.
  81  */
  82 static struct clk *clk;
  83
  84 /*
  85  * Enabling and disabling functions.
  86  */
  87 static void coh901327_enable(u16 timeout)
  88 {
  89         u16 val;
  90         unsigned long freq;
  91         unsigned long delay_ns;
  92
  93         clk_enable(clk);
  94         /* Restart timer if it is disabled */
  95         val = readw(virtbase + U300_WDOG_D2R);
  96         if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
  97                 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
  98                        virtbase + U300_WDOG_RR);
  99         /* Acknowledge any pending interrupt so it doesn't just fire off */
 100         writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 101                virtbase + U300_WDOG_IER);
 102         /*
 103          * The interrupt is cleared in the 32 kHz clock domain.
 104          * Wait 3 32 kHz cycles for it to take effect
 105          */
 106         freq = clk_get_rate(clk);
 107         delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
 108         delay_ns = 3 * delay_ns; /* Wait 3 cycles */
 109         ndelay(delay_ns);
 110         /* Enable the watchdog interrupt */
 111         writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
 112         /* Activate the watchdog timer */
 113         writew(timeout, virtbase + U300_WDOG_TR);
 114         /* Start the watchdog timer */
 115         writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
 116         /*
 117          * Extra read so that this change propagate in the watchdog.
 118          */
 119         (void) readw(virtbase + U300_WDOG_CR);
 120         val = readw(virtbase + U300_WDOG_D2R);
 121         clk_disable(clk);
 122         if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 123                 dev_err(parent,
 124                         "%s(): watchdog not enabled! D2R value %04x\n",
 125                         __func__, val);
 126 }
 127
 128 static void coh901327_disable(void)
 129 {
 130         u16 val;
 131
 132         clk_enable(clk);
 133         /* Disable the watchdog interrupt if it is active */
 134         writew(0x0000U, virtbase + U300_WDOG_IMR);
 135         /* If the watchdog is currently enabled, attempt to disable it */
 136         val = readw(virtbase + U300_WDOG_D2R);
 137         if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
 138                 writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
 139                        virtbase + U300_WDOG_D1R);
 140                 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 141                        virtbase + U300_WDOG_D2R);
 142                 /* Write this twice (else problems occur) */
 143                 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 144                        virtbase + U300_WDOG_D2R);
 145         }
 146         val = readw(virtbase + U300_WDOG_D2R);
 147         clk_disable(clk);
 148         if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 149                 dev_err(parent,
 150                         "%s(): watchdog not disabled! D2R value %04x\n",
 151                         __func__, val);
 152 }
 153
 154 static int coh901327_start(struct watchdog_device *wdt_dev)
 155 {
 156         coh901327_enable(wdt_dev->timeout * 100);
 157         return 0;
 158 }
 159
 160 static int coh901327_stop(struct watchdog_device *wdt_dev)
 161 {
 162         coh901327_disable();
 163         return 0;
 164 }
 165
 166 static int coh901327_ping(struct watchdog_device *wdd)
 167 {
 168         clk_enable(clk);
 169         /* Feed the watchdog */
 170         writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 171                virtbase + U300_WDOG_FR);
 172         clk_disable(clk);
 173         return 0;
 174 }
 175
 176 static int coh901327_settimeout(struct watchdog_device *wdt_dev,
 177                                 unsigned int time)
 178 {
 179         wdt_dev->timeout = time;
 180         clk_enable(clk);
 181         /* Set new timeout value */
 182         writew(time * 100, virtbase + U300_WDOG_TR);
 183         /* Feed the dog */
 184         writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 185                virtbase + U300_WDOG_FR);
 186         clk_disable(clk);
 187         return 0;
 188 }
 189
 190 static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
 191 {
 192         u16 val;
 193
 194         clk_enable(clk);
 195         /* Read repeatedly until the value is stable! */
 196         val = readw(virtbase + U300_WDOG_CR);
 197         while (val & U300_WDOG_CR_VALID_IND)
 198                 val = readw(virtbase + U300_WDOG_CR);
 199         val &= U300_WDOG_CR_COUNT_VALUE_MASK;
 200         clk_disable(clk);
 201         if (val != 0)
 202                 val /= 100;
 203
 204         return val;
 205 }
 206
 207 /*
 208  * This interrupt occurs 10 ms before the watchdog WILL bark.
 209  */
 210 static irqreturn_t coh901327_interrupt(int irq, void *data)
 211 {
 212         u16 val;
 213
 214         /*
 215          * Ack IRQ? If this occurs we're FUBAR anyway, so
 216          * just acknowledge, disable the interrupt and await the imminent end.
 217          * If you at some point need a host of callbacks to be called
 218          * when the system is about to watchdog-reset, add them here!
 219          *
 220          * NOTE: on future versions of this IP-block, it will be possible
 221          * to prevent a watchdog reset by feeding the watchdog at this
 222          * point.
 223          */
 224         clk_enable(clk);
 225         val = readw(virtbase + U300_WDOG_IER);
 226         if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
 227                 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 228                        virtbase + U300_WDOG_IER);
 229         writew(0x0000U, virtbase + U300_WDOG_IMR);
 230         clk_disable(clk);
 231         dev_crit(parent, "watchdog is barking!\n");
 232         return IRQ_HANDLED;
 233 }
 234
 235 static const struct watchdog_info coh901327_ident = {
 236         .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 237         .identity = DRV_NAME,
 238 };
 239
 240 static struct watchdog_ops coh901327_ops = {
 241         .owner = THIS_MODULE,
 242         .start = coh901327_start,
 243         .stop = coh901327_stop,
 244         .ping = coh901327_ping,
 245         .set_timeout = coh901327_settimeout,
 246         .get_timeleft = coh901327_gettimeleft,
 247 };
 248
 249 static struct watchdog_device coh901327_wdt = {
 250         .info = &coh901327_ident,
 251         .ops = &coh901327_ops,
 252         /*
 253          * Max timeout is 327 since the 10ms
 254          * timeout register is max
 255          * 0x7FFF = 327670ms ~= 327s.
 256          */
 257         .min_timeout = 0,
 258         .max_timeout = 327,
 259 };
 260
 261 static int __exit coh901327_remove(struct platform_device *pdev)
 262 {
 263         watchdog_unregister_device(&coh901327_wdt);
 264         coh901327_disable();
 265         free_irq(irq, pdev);
 266         clk_unprepare(clk);
 267         clk_put(clk);
 268         iounmap(virtbase);
 269         release_mem_region(phybase, physize);
 270         return 0;
 271 }
 272
 273 static int __init coh901327_probe(struct platform_device *pdev)
 274 {
 275         int ret;
 276         u16 val;
 277         struct resource *res;
 278
 279         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 280         if (!res)
 281                 return -ENOENT;
 282
 283         parent = &pdev->dev;
 284         physize = resource_size(res);
 285         phybase = res->start;
 286
 287         if (request_mem_region(phybase, physize, DRV_NAME) == NULL) {
 288                 ret = -EBUSY;
 289                 goto out;
 290         }
 291
 292         virtbase = ioremap(phybase, physize);
 293         if (!virtbase) {
 294                 ret = -ENOMEM;
 295                 goto out_no_remap;
 296         }
 297
 298         clk = clk_get(&pdev->dev, NULL);
 299         if (IS_ERR(clk)) {
 300                 ret = PTR_ERR(clk);
 301                 dev_err(&pdev->dev, "could not get clock\n");
 302                 goto out_no_clk;
 303         }
 304         ret = clk_prepare_enable(clk);
 305         if (ret) {
 306                 dev_err(&pdev->dev, "could not prepare and enable clock\n");
 307                 goto out_no_clk_enable;
 308         }
 309
 310         val = readw(virtbase + U300_WDOG_SR);
 311         switch (val) {
 312         case U300_WDOG_SR_STATUS_TIMED_OUT:
 313                 dev_info(&pdev->dev,
 314                         "watchdog timed out since last chip reset!\n");
 315                 coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
 316                 /* Status will be cleared below */
 317                 break;
 318         case U300_WDOG_SR_STATUS_NORMAL:
 319                 dev_info(&pdev->dev,
 320                         "in normal status, no timeouts have occurred.\n");
 321                 break;
 322         default:
 323                 dev_info(&pdev->dev,
 324                         "contains an illegal status code (%08x)\n", val);
 325                 break;
 326         }
 327
 328         val = readw(virtbase + U300_WDOG_D2R);
 329         switch (val) {
 330         case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
 331                 dev_info(&pdev->dev, "currently disabled.\n");
 332                 break;
 333         case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
 334                 dev_info(&pdev->dev,
 335                          "currently enabled! (disabling it now)\n");
 336                 coh901327_disable();
 337                 break;
 338         default:
 339                 dev_err(&pdev->dev,
 340                         "contains an illegal enable/disable code (%08x)\n",
 341                         val);
 342                 break;
 343         }
 344
 345         /* Reset the watchdog */
 346         writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
 347
 348         irq = platform_get_irq(pdev, 0);
 349         if (request_irq(irq, coh901327_interrupt, 0,
 350                         DRV_NAME " Bark", pdev)) {
 351                 ret = -EIO;
 352                 goto out_no_irq;
 353         }
 354
 355         clk_disable(clk);
 356
 357         ret = watchdog_init_timeout(&coh901327_wdt, margin, &pdev->dev);
 358         if (ret < 0)
 359                 coh901327_wdt.timeout = 60;
 360
 361         ret = watchdog_register_device(&coh901327_wdt);
 362         if (ret == 0)
 363                 dev_info(&pdev->dev,
 364                          "initialized. timer margin=%d sec\n", margin);
 365         else
 366                 goto out_no_wdog;
 367
 368         return 0;
 369
 370 out_no_wdog:
 371         free_irq(irq, pdev);
 372 out_no_irq:
 373         clk_disable_unprepare(clk);
 374 out_no_clk_enable:
 375         clk_put(clk);
 376 out_no_clk:
 377         iounmap(virtbase);
 378 out_no_remap:
 379         release_mem_region(phybase, SZ_4K);
 380 out:
 381         return ret;
 382 }
 383
 384 #ifdef CONFIG_PM
 385
 386 static u16 wdogenablestore;
 387 static u16 irqmaskstore;
 388
 389 static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
 390 {
 391         irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
 392         wdogenablestore = readw(virtbase + U300_WDOG_D2R);
 393         /* If watchdog is on, disable it here and now */
 394         if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 395                 coh901327_disable();
 396         return 0;
 397 }
 398
 399 static int coh901327_resume(struct platform_device *pdev)
 400 {
 401         /* Restore the watchdog interrupt */
 402         writew(irqmaskstore, virtbase + U300_WDOG_IMR);
 403         if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
 404                 /* Restart the watchdog timer */
 405                 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
 406                        virtbase + U300_WDOG_RR);
 407                 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 408                        virtbase + U300_WDOG_FR);
 409         }
 410         return 0;
 411 }
 412 #else
 413 #define coh901327_suspend NULL
 414 #define coh901327_resume  NULL
 415 #endif
 416
 417 /*
 418  * Mistreating the watchdog is the only way to perform a software reset of the
 419  * system on EMP platforms. So we implement this and export a symbol for it.
 420  */
 421 void coh901327_watchdog_reset(void)
 422 {
 423         /* Enable even if on JTAG too */
 424         writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
 425                virtbase + U300_WDOG_JOR);
 426         /*
 427          * Timeout = 5s, we have to wait for the watchdog reset to
 428          * actually take place: the watchdog will be reloaded with the
 429          * default value immediately, so we HAVE to reboot and get back
 430          * into the kernel in 30s, or the device will reboot again!
 431          * The boot loader will typically deactivate the watchdog, so we
 432          * need time enough for the boot loader to get to the point of
 433          * deactivating the watchdog before it is shut down by it.
 434          *
 435          * NOTE: on future versions of the watchdog, this restriction is
 436          * gone: the watchdog will be reloaded with a default value (1 min)
 437          * instead of last value, and you can conveniently set the watchdog
 438          * timeout to 10ms (value = 1) without any problems.
 439          */
 440         coh901327_enable(500);
 441         /* Return and await doom */
 442 }
 443
 444 static const struct of_device_id coh901327_dt_match[] = {
 445         { .compatible = "stericsson,coh901327" },
 446         {},
 447 };
 448
 449 static struct platform_driver coh901327_driver = {
 450         .driver = {
 451                 .owner  = THIS_MODULE,
 452                 .name   = "coh901327_wdog",
 453                 .of_match_table = coh901327_dt_match,
 454         },
 455         .remove         = __exit_p(coh901327_remove),
 456         .suspend        = coh901327_suspend,
 457         .resume         = coh901327_resume,
 458 };
 459
 460 module_platform_driver_probe(coh901327_driver, coh901327_probe);
 461
 462 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 463 MODULE_DESCRIPTION("COH 901 327 Watchdog");
 464
 465 module_param(margin, uint, 0);
 466 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 467
 468 MODULE_LICENSE("GPL");
 469 MODULE_ALIAS("platform:coh901327-watchdog");